Fig. 4. Flume showing the inlet and outlet ports to manipulate the different flow paths that occur in the soil, rainfall simulator, and soil redox potential (Eh) and pH electrodes. I_b, inflow port at the bottom of the flume; I_t, inflow port at the top of the flume; O_b, outflow port at the bottom of the flume; O_t, outflow port at the top of the flume.